Discipling by the Apostles
Mat 28:19-20 Go therefore and make disciples of all the nations, baptizing them in the name of the Father and of the Son and of the Holy Spirit, teaching them to observe all things that I have commanded you; and lo, I am with you always, even to the end of the age." Amen.
The disciples of Jesus went out to preach the gospel of grace to both Jews and Gentiles, baptised all those who believed and then discipled them by teaching them to keep all His commandments or the apostle's doctrines.
Act 2:41-42 Then those who gladly received his word were baptized; and that day about three thousand souls were added to them. And they continued steadfastly in the apostles' doctrine and fellowship, in the breaking of bread, and in prayers.
Doctrines of the Apostles
Act 15:24, 27-29 Since we have heard that some who went out from us have troubled you with words, unsettling your souls, saying, "You must be circumcised and keep the law" —to whom we gave no such commandment—... We have therefore sent Judas and Silas, who will also report the same things by word of mouth. For it seemed good to the Holy Spirit, and to us, to lay upon you no greater burden than these necessary things: that you abstain from things offered to idols, from blood, from things strangled, and from sexual immorality. If you keep yourselves from these, you will do well.
All Christians must follow the teachings of our Lord Jesus only, and they must not observe the law in the Old Covenant, which was made obsolete by the New Covenant of the blood of Jesus shed on the cross.
However, they must continue to observe the followings:-
1. abstain from things offered to idols
The Gentile converts had given up idolatry upon their salvation, and they were reminded not to eat food offered to idol in temples along with idolaters.
2. from blood,
3. from things strangled
Gen 9:3-4 Every moving thing that lives shall be food for you. I have given you all things, even as the green herbs. But you shall not eat flesh with its life, that is, its blood.
After the flood, God had given all animal as food for man except that we must not eat blood nor meat with blood not drained out such as those animals strangled to death.
Note - Pork and other unclean food were forbidden only under the Old Covenant but they are clean for Christians under grace.
4. from sexual immorality
Mat 19:5-8 and said, 'For this reason a man shall leave his father and mother and be joined to his wife, and the two shall become one flesh'? So then, they are no longer two but one flesh. Therefore what God has joined together, let not man separate." They said to Him, "Why then did Moses command to give a certificate of divorce, and to put her away?" He said to them, "Moses, because of the hardness of your hearts, permitted you to divorce your wives, but from the beginning it was not so."
God joined Adam and Eve together in marriage, and forbid anything to separate any married couple - so no divorce, adultery nor sexual immorality.
Gal 3:10 For as many as are of the works of the law are under the curse; for it is written, "Cursed is everyone who does not continue in all things which are written in the book of the law, to do them."
Any Christian keeping any part of the Law is under the curse or damnation. I thank God that the word of God is perfect for the things (4 items above) that Christians are to abstain from, were instructions given since the time of Noah and not under Mosiac Law.